The present invention relates generally to containers having a sealed opening, and more particularly to a closure seal for sealing an opening of a container.
Packaging for certain types of products, and for bottled liquid products in particular, often require a seal that is both peelable (i.e., easy one-piece removal) and leak-proof and that retains the freshness of the contents of the container. Once opened, the freshness seal will be broken. It is, therefore, desirable that the seal be adequately and securely retained over the opening of the container prior to removal. However, it is also highly desirable that the seal be easily removable by the consumer of the product.
Many different types of closure seals are known that adequately perform the peeling, leak prevention and freshness seal objectives. Some of these closure seal designs also incorporate some form of structure or device that assists in removal of the seal. Many simple closure seal designs include a tab extending from a peripheral edge of the seal that can be grasped by a user to remove the closure seal from the container. However, it is often difficult for an individual to grip and hold the tab. Moreover, such a tab also requires special die punch equipment to cut the protruding tab. Yet further, the peripherally extending tab can interfere with good sealing due to the need to accommodate the tab in a cap, e.g., by folding over the tab during capping.
More sophisticated examples of pull-tabs are also known.
For example, U.S. Pat. No. 5,433,992 discloses a seal construction wherein a multi-layer seal is formed with each of the layers adhere to one another. However, a portion of the seal includes a non-adhered section to between two layers. The exposed upper portion of this section of the seal acts as a pull-tab that can be gripped by the user to release the seal from the container.
Selig Sealing Products"" own U.S. Pat. No. 5,702,015 discloses a closure seal that also has a pull-tab extending from an upper surface of the seal. The seal disclosed in this patent is formed having a first layer and a second layer of the same material that are co-extruded so as to form a single layer with a portion of the layer forming a pull tab. One advantage of this structure is the elimination of possible environmentally sensitive chemicals used in providing adhesive to secure a second layer to for the pull tab as is down in U.S. Pat. No. 5,433,992.
One problem with many of these closure seals and pull-tabs are that the pull-tabs are thin and difficult to grasp. Formation of a thicker pull-tab would improve the removability characteristics of the closure seal. However, it is desirable not to increase the number of material layers in order to accomplish this objective because of material and manufacturing cost concerns. Another drawback associated with many pull-tab constructions is that, during the manufacturing process, adhesives and/or other bonding techniques must be applied to the sheet or blank of material intermittently over specified areas in order to accomplish formation of the pull-tab. These specific and precise manufacturing techniques add expense to the manufacturing and design processes. A further drawback of many pull-tab designs is that only one pull-tab is available for the consumer to grasp. The pull-tab may be inadvertently partly adhered to another portion of the seal and difficult to initially lift and grasp, or may at least initially be difficult to detect.
It is, therefore, one object of the present invention to provide a closure seal for an opening of a container that provides a pair of pull-tabs available to assist in removal of the closure seal from the container. It is another object of the present invention to provide a closure seal that, when the pair of pull-tabs are utilized together, provides a thicker gripping surface making removal, one-piece peel removal in particular, of the closure seal easier. It is a further object of the present invention to provide a closure seal that does not require specialized positioning of adhesives or other bonding techniques applied to or performed on the material strip or blank from which the closure seals are fabricated. It is another object of the present invention to provide a material blank or strip for forming a plurality of the closure seals of the invention. It is a further object of the present invention to provide a method of fabricating closure seals for containers.
These and other objects, features and advantages are provided by the closure seal, the material blank, and the method of fabricating closure seals of the present invention. In one embodiment, a seal for a container opening has a backing layer and a seal layer for connecting to and covering an opening of the container. A pull-tab forming layer is sandwiched between the backing layer and the seal layer. The pull-tab forming layer has a heat sealable side joined to the backing layer and an opposite heat resistant side joined to the seal layer. The pull-tab layer also has a hinge disposed near the center of the seal that joins the backing layer and the seal layer. The backing layer and a portion of the pull-tab forming layer define a pair of opposed pull-tabs extending from the hinge.
In one embodiment, the pull-tab forming layer has a heat sealable sub-layer and a heat resistant sub-layer joined to one another. The pull-tab forming layer is folded to form a central stem from which two pull tabs extend in opposite directions.
In one embodiment, the pull-tab forming layer has a heat sealable sub-layer and a heat resistant sub-layer joined to one another. The pull-tab forming layer is folded to form a central stem from which the pull tabs extend and having an upper horizontal portion with a top surface that defines the heat sealable side of the. pull-tab forming layer. The top surface is formed entirely of exposed, adjoining sections of the heat sealable sub-layer. The stem also has a lower horizontal portion having a bottom surface that defines the heat resistant side of the pull-tab forming layer. The lower horizontal portion is formed entirely of an exposed section of the heat resistant sub-layer.
In one embodiment, the pull-tab forming layer has an upper heat sealable sub-layer joined to a lower heat resistant sub-layer. The pull-tab forming layer is folded to generally form a central stem from which the pull tabs extend and having an upper and lower horizontal portion and a vertical portion extending between the upper and lower horizontal portions. The vertical portion defines the hinge and is arranged so that the upper horizontal portion is joined to the backing layer to define the opposed pair of pull-tabs.
In one embodiment, the pull-tab forming layer has an upper heat sealable sub-layer joined to a lower heat resistant sub-layer. Opposite ends of the pull-tab forming layer are folded about 180xc2x0 relative to linear section and back onto a first linear section of the pull-tab forming layer so that the opposite ends extend back toward one another. The remaining portions of the opposite end are folded about 90xc2x0 relative to the linear section so that the heat sealable sub-layer of second linear sections of the opposite ends abut one another. Last remaining portions of the opposite ends are each folded about 90xc2x0 away from one another so that the last remaining portions beyond the second linear sections extend parallel to and away from one another. The heat sealable sub-layer material of the last remaining portions is joined to the backing layer and the heat resistant sub-layer of the last remaining portions faces the first linear section. The second linear section defines the hinge and the last remaining portions of the opposite ends and the backing layer together define the opposed pair of pull-tabs.
In one embodiment, the backing layer is formed from a thermoset polyester material. In another embodiment, the seal layer is an induction aluminum foil layer.
In one embodiment, the seal layer further includes a bottom surface with a heat activated adhesive carried thereon for attaching the seal to the container.
In one embodiment, the seal layer is joined to the pull-tab forming layer by a bonding material layer such an adhesive system.
In one embodiment, the seal layer is joined to the pull-tab forming layer by an extrusion bonding system.
In one embodiment, the seal layer is joined to the pull-tab forming layer by polyethelene copolymer.
In one embodiment, the seal layer is joined to the pull-tab forming layer by a dry band system.
In one embodiment, the heat sealable side of the pull-tab forming layer is formed from a thermoplastic material such as polyethylene.
In another embodiment, the heat resistant side of the pull-tab forming layer is formed from thermoset polyester.
In one embodiment of the invention, a material blank for forming a plurality of seals for covering container openings includes a backing layer having an upper and a lower surface. The blank also includes a seal layer having an upper and lower surface. The blank further has a pull-tab forming layer having an upper surface joined to the lower surface of the backing layer and having a lower surface joined to the upper surface of the seal layer. The pull-tab forming layer includes a first sub-layer of a heat sealable material with an exposed upper sub-surface and a lower sub-surface. The pull-tab forming layer also has a second sub-layer of a heat resistant material having an exposed lower sub-surface and an upper sub-surface joined to the lower sub-surface of the first sub-layer of material. Each elongate section generally has a central stem in cross section with an upper horizontal portion having a top surface that in combination with the upper horizontal portions of the adjacent sections define the heat sealable side of the pull-tab layer. The top surfaces of the upper horizontal portions are formed entirely by exposed sections of the heat sealable sub-layer.
In one embodiment, the pull-tab forming layer of the material blank has a plurality of vertical hinge portions each extending perpendicularly from the upper horizontal portion of each longitudinal section. Each vertical hinge portion includes two abutting first sub-layers of heat sealable material sandwiched between a pair of second sub-layers of heat resistant material. A lower horizontal portion extends parallel with each of the upper horizontal portions. Each lower horizontal portion has two abutting first sub-layers of heat sealable material substantially surrounded by the second sub-layer of heat resistant material. An air pocket is disposed between the vertical hinge portions and between parts of the upper and lower horizontal portions of each adjacent pair of longitudinal sections.
In one embodiment, a backing layer is a continuous sheet of thermoplastic polyester material. In another embodiment, the seal layer is a continuous sheet of aluminum foil adhered to the bottom surface of the pull-tab forming layer by an adhesive layer completely covering the bottom surface. In a further embodiment, the first sub-layer of heat sealable material is formed from thermoplastic polyethylene and the second sub-layer of heat resistant material is formed from thermoset polyester.
In another embodiment of the invention, a method of forming a plurality of seals for covering container openings includes first providing a backing layer having an upper and a lower surface. The method also includes providing a seal layer also having an upper and lower surface. A lower sub-surface of a first sub-layer of a heat sealable material is then joined with an upper sub-surface of a second sub-layer of a heat resistant material. The joined first and second sub-layers are then folded multiple times to form a plurality of adjacent parallel and elongate sections. Each elongate section generally has a central stem in cross section with an upper horizontal portion, a lower horizontal portion, and a vertical hinge portion. The upper horizontal portions together define a heat sealable top surface of the pull-tab forming layer. The lower horizontal portions together define a heat resistant bottom surface of the pull-tab forming layer. The backing layer is then joined to the pull-tab forming layer by securing the heat sealable top surface of the pull-tab forming layer to the backing layer bottom surface. The seal layer is then joined to the pull-tab forming layer by securing the heat resistant lower surface of the pull-tab forming layer to the seal layer upper surface. A plurality of seal shapes are then punched from the joined layers. However, due to die punch layout nesting, each seal may overlap adjacent elongated sections.
In one embodiment, the step of punching further includes punching a plurality of circular seal shapes from the adhered layers wherein a portion of one of the vertical hinge portions of an elongate section of the adhered layers generally bisects each of the circular seal shapes.
In one embodiment, the step of securing the backing layer to the pull-tab forming layer further includes bonding via an adhesive system, an extrusion system or a thermal lamination system, to secure the upper surface of the pull-tab forming layer to the heat sealable material to the backing layer.
In one embodiment, the step of adhering the seal layer and the pull-tab forming layer further includes applying a bonding material over the entire surface of either the seal layer or the pull-tab forming layer and bonding the two layers together.